[PATCH bpf-next 1/5] bpf: add bpf_strncmp helper
flat view
STALE1769d
SUPERSEDED
From: Hou Tao <hidden>
Date: 2021-11-30 14:07:03
Also in:
bpf
Subsystem:
bpf [core], bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
Revision v1 of 3 in this series.
Revisions (3)
- rfc [diff vs current]
- v1 current
- v2 [diff vs current]
The helper compares two strings: one string is a null-terminated read-only string, and another string has const max storage size but doesn't need to be null-terminated. It can be used to compare file name in tracing or LSM program. Signed-off-by: Hou Tao <redacted> --- include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 11 +++++++++++ kernel/bpf/helpers.c | 16 ++++++++++++++++ tools/include/uapi/linux/bpf.h | 11 +++++++++++ 4 files changed, 39 insertions(+)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a7cbc29b0994..685c8fe5c0be 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h@@ -2165,6 +2165,7 @@ extern const struct bpf_func_proto bpf_sk_setsockopt_proto; extern const struct bpf_func_proto bpf_sk_getsockopt_proto; extern const struct bpf_func_proto bpf_kallsyms_lookup_name_proto; extern const struct bpf_func_proto bpf_find_vma_proto; +extern const struct bpf_func_proto bpf_strncmp_proto; const struct bpf_func_proto *tracing_prog_func_proto( enum bpf_func_id func_id, const struct bpf_prog *prog);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a69e4b04ffeb..afdc52efa4a1 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h@@ -4957,6 +4957,16 @@ union bpf_attr { * **-ENOENT** if *task->mm* is NULL, or no vma contains *addr*. * **-EBUSY** if failed to try lock mmap_lock. * **-EINVAL** for invalid **flags**. + * + * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) + * Description + * Do strncmp() between **s1** and **s2**. **s1** doesn't need + * to be null-terminated and **s1_sz** is the maximum storage + * size of **s1**. **s2** must be a read-only string. + * Return + * An integer less than, equal to, or greater than zero + * if the first **s1_sz** bytes of **s1** is found to be + * less than, to match, or be greater than **s2**. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \
@@ -5140,6 +5150,7 @@ union bpf_attr { FN(skc_to_unix_sock), \ FN(kallsyms_lookup_name), \ FN(find_vma), \ + FN(strncmp), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 1ffd469c217f..a7d3a8d48e00 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c@@ -565,6 +565,20 @@ const struct bpf_func_proto bpf_strtoul_proto = { }; #endif +BPF_CALL_3(bpf_strncmp, const char *, s1, u32, s1_sz, const char *, s2) +{ + return strncmp(s1, s2, s1_sz); +} + +const struct bpf_func_proto bpf_strncmp_proto = { + .func = bpf_strncmp, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_MEM, + .arg2_type = ARG_CONST_SIZE, + .arg3_type = ARG_PTR_TO_CONST_STR, +}; + BPF_CALL_4(bpf_get_ns_current_pid_tgid, u64, dev, u64, ino, struct bpf_pidns_info *, nsdata, u32, size) {
@@ -1378,6 +1392,8 @@ bpf_base_func_proto(enum bpf_func_id func_id) return &bpf_ringbuf_query_proto; case BPF_FUNC_for_each_map_elem: return &bpf_for_each_map_elem_proto; + case BPF_FUNC_strncmp: + return &bpf_strncmp_proto; default: break; }
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index a69e4b04ffeb..afdc52efa4a1 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h@@ -4957,6 +4957,16 @@ union bpf_attr { * **-ENOENT** if *task->mm* is NULL, or no vma contains *addr*. * **-EBUSY** if failed to try lock mmap_lock. * **-EINVAL** for invalid **flags**. + * + * long bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) + * Description + * Do strncmp() between **s1** and **s2**. **s1** doesn't need + * to be null-terminated and **s1_sz** is the maximum storage + * size of **s1**. **s2** must be a read-only string. + * Return + * An integer less than, equal to, or greater than zero + * if the first **s1_sz** bytes of **s1** is found to be + * less than, to match, or be greater than **s2**. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \
@@ -5140,6 +5150,7 @@ union bpf_attr { FN(skc_to_unix_sock), \ FN(kallsyms_lookup_name), \ FN(find_vma), \ + FN(strncmp), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.29.2